A computational study of the effects of linear doping profile on the high-frequency and switching performances of hetero-material-gate CNTFETs

• Published in: Journal of semiconductors Vol. 34; no. 12; pp. 34 - 39
• Main Author: 王伟 李娜 任雨舟 郑丽芬 蒋俊杰 陈小平 李金 王凯 夏春萍
• Format: Journal Article
• Language: English
• Published: 01.12.2013
• Subjects: Channels; Computer simulation; Doping; Drains; Optimization; Poisson equation; Semiconductors; Switching; 开关性能; 异质材料; 掺杂分布; 电晶体; 碳管; 线性; 非平衡格林函数; 高频特性
• ISSN: 1674-4926
• DOI: 10.1088/1674-4926/34/12/124002

The effects of linear doping profile near the source and drain contacts on the switching and high- frequency characteristics for conventional single-material-gate CNTFET （C-CNTFET） and hetero-material-gate CNTFET （HMG-CNTFET） have been theoretically investigated by using a quantum kinetic model. This model is based on two-dimensional non-equilibrium Green＇s functions （NEGF） solved self-consistently with Poisson＇s equations. The simulation results show that at a CNT channel length of 20 nm with chirality （7, 0）, the intrinsic cutoff frequency of C-CNTFETs reaches up to a few THz. In addition, a comparison study has been performed between C-and HMG-CNTFETs. For the C-CNTFET, results reveal that a longer linear doping length can improve the cutoff frequency and switching speed. However, it has the reverse effect on on/off current ratios. To improve the on/off current ratios performance of CNTFETs and overcome short-channel effects （SCEs） in high-performance device applications, a novel CNTFET structure with a combination of an HMG and linear doping profile has been proposed. It is demonstrated that the HMG structure design with an optimized linear doping length has improved high-frequency and switching performances as compared to C-CNTFETs. The simulation study may be useful for understanding and optimizing high-performance of CNTFETs and assessing the reliability of CNTFETs for prospective applications.